I’m interested.
I wouldn’t use royal blue LEDs! There is sufficient evidence that they will damage your eyes.
They pretend to be brighter in specs (higher lumen values) but visible output is similar to standard blue.
Instead of using multiple 7135 for each color LED you might consider a single D882 transistor per LED, I’m using them in my RGBW D4 EDC since January 2018 without any problems. D882 are slower than 7135 so I recommend reducing the PWM rate for near moonlight levels.
I prefer a double head light (not double-barrel but one head at each end), similar to my RGBW Q8 but sized as a D4. One powerful quad head with TIR for a couple of thousands lumens and one head with 4 color LEDs behind a TIR. This would require a special tube which leads the positive terminal of the cell to the rear head (hint: FW3A).